This project investigates intergroup violence prevent among youth through the study of predictors and mediators of prejudice reduction and conflict resolution. A four-part model of prejudice reduction is developed and tested. It is based on principles derived from Allport's (1954/59) seminar work, Berry, Trimble, and Olmedo's (1986) acculturation theory, and recent updates of social categorization theory (e.g., Hornsey and Hogg, 2000). In the derived model, openness to engaging in activities with members of other racial/ethnic groups plays a pivotal role, while strength of one's racial identity is of much less importance in mediating intergroup affective bias reduction. This model is compared to alternatives that emphasize participants' willingness to view ingroup and outgroup members as a common ingroup. Major elements of the four-part prejudice reduction model are tested in a series of quasi-experiments conducted in multi-racial high school classes. This empirical work uses pre-/post-intervention measures of 1) young people's perception of the classroom interracial climate, 2) their affective intergroup prejudice, and 3) psychological mediators of change in such prejudice. In these school-based studies, pairs of college student facilitators initiate small group discussion about racial issuers among the high school students, using systematic variations of an approved curriculum. Mediational analyses, analysis of variance, multiple regression, and structural equations modeling are used in various statistical analyses of these data. One laboratory study involving college students tests several of the causal relationships specified in the four-part model for prejudice reduction by joint manipulating outgroup orientation and strength of subgroup identify. Another university-based laboratory study tests the extent to which level of social self-esteem and level of threat to ingroup identify influence the tendency to make biased judgement about an outgroup. In the conflict resolution portion of the project, insights from the aforementioned theoretical and empirical work on intergroup prejudice reduction are brought to bear on the development, implementation, and evaluation of intergroup conflict services for youth.